Let's Make Robots!

How to build a simple radio receiver ?


After I read these three threads : http://letsmakerobots.com/node/77  ,http://letsmakerobots.com/node/5194 

, http://letsmakerobots.com/node/5916 , i wondered if it is possible to build radio transmitters and receivers yourself , so i googled it and found this page to build a simple AM transmitter : http://sci-toys.com/scitoys/scitoys/radio/am_transmitter.html .

I could not find anything on how to build an AM receiver to a specific frequency (e.g. 1Mhz) thou.

My aim is to simply transmit data ,like fritsl explained. Does anybody know how to build something like that , or do I have to buy these parts?

Thank you!



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Thank you!

I will try it soon 

Having a look on that site, is shows how to make radio receivers, so you could try one of these, and fix the frequency to 1MhZ. Or just find a cheap AM radio, take it apart, use the circuitry in there. Just tune it to the correct frequency, and fix it, and the volume will probably be a variable resistor, so take it out and replace with a fixed one, then use the wires to the speakers for the signal. Although you may want the un-amplified signal so find that before it goes through the amplifier circuitry (this might cut out the variable resistor anyway).

 I once made a radio transmitter and a receiver on an 'electronic playground' I can upload the schematics if you want.

Is there a simple way to fix the receiver to the frequency or do i have to tune it in and fix it ?

A variable capacitor most probably controls the tuning as in: http://sci-toys.com/scitoys/scitoys/radio/three_penny/three_penny.html I don't know if it is possible to measure what the capacitance is set to, and find a capacitor of that value to replace it. It might be easier to use a variable one and fix it in place.

You might want to have a look at this also on that site: http://sci-toys.com/scitoys/scitoys/computers/radio/computer_controlled_transmitter.html

one other thing to add is that using the frequency band for radio stations to transmit data is probably not a good idea, as you will get alot of interference, and it might be illegal depending on where you are.